The present invention relates generally to electrical temperature measuring devices, and more particulary to an improved resistance-type sensor for a temperature probe.
Many electrical temperature-measuring devices include an elongate probe having a temperature sensor at one end. Such probes take a variety of forms, depending on their intended use. For example, U.S. Pat. No. 3,308,666 to Anderson et al. describes several ceramic-bodied probes having sensing elements made of refractory metal oxides for measuring extremely high temperatures (above approx. 1100.degree. C.). Such sensors are not suitable for use at lower temperatures, however.
An electrical clinical thermometer system including a probe adapted for insertion into a body cavity is the subject of U.S. Pat. No. 3,776,040 to Gould. The temperature sensor for the probe, which is intended to be thrown away after each use, comprises a gold film formed in a serpentine pattern on a flat base member. U.S. Pat. No. 3,893,058 to Keith concerns a thermister-type clinical probe for an electronic thermometer. Designed to measure the average temperature of its surroundings, the probe's sensor comprises a sprial strip of thermistor material wound around a tubular foundation member for the probe. In a U.S. Pat. to Adams, No. 3,915,003, an electronic clinical thermometer probe is described that includes a metal film (platinum, nickel, chromium or titanium) temperature-sensing resistor deposited on a disk of a high heat conductivity dielectric (alumina, beryllia, etc.). A disposable plastic sheath slips over the temperature-sensing end of the probe to eliminate the need for sterilizing it after each use.
Probes of the type just described and other prior art temperature probes (e.g., the P6058 and P6430 probes sold by Tektronix, Inc.) are not well suited for measurement applications requiring high accuracy over a wide temperature range together with high sensitivity and stability, quick response, and the ability to measure surface temperatures accurately.